The overdose of two Toronto-area teens last month has been linked to a synthetic form of cannabis, not opioid-tainted marijuana as police initially suspected.

On May 15, officers responded to a small gathering of friends in Milton and found a 16-year-old boy and an 18-year-old man unconscious with vomit around them and the stench of cannabis on the back porch of a house, according to the Halton Regional Police Service.

Police quickly administered the opioid antidote naloxone to both victims, with one waking up right away and the other needing another dose before both were transferred to hospital.

On Wednesday, the department contradicted its initial assertion by releasing the results of blood work proving the teens had smoked a synthetic cannabinoid, according to Inspector Kevin Maher.

“It’s a much more dangerous substance [than cannabis]; there’s no quality control on its creation,” Insp. Maher said. “Just like any synthetic drug, it has varying levels of chemicals and concentrations and, in this case, it obviously caused some very serious medical symptoms.”

Halton Regional Police now joins a growing list of authorities in North America, including Vancouver’s force in 2015, that have had to correct similar claims about fentanyl-tainted cannabis.

Synthetic cannabinoids are created by spraying different combinations of chemicals onto mixtures of simple herbs. The resulting concoction is often sold illegally in tobacco shops, convenience stores and on the streets under the name “spice” or “K2."

Insp. Maher said the teens told investigators that they purchased the drug at a Toronto “head shop” or cannabis paraphernalia store and believed they were purchasing another more potent hallucinogen called salvia.

In 2013, Health Canada released a warning about these types of synthetic cannabinoids and declared all synthetic preparations of cannabis to be controlled substances, noting their effects could include panic attacks, memory loss, acute psychosis, seizures, chest pain and vomiting.

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“These products are often marketed as ‘smokeable herbal incense,' ‘exotic herbal incense,’ ‘legal highs’ or as alternatives to marijuana, and are believed to be smoked by consumers for their cannabis-like effects, even though they are often labelled as 'not for human consumption,’ ” the agency said.

Mass overdoses of the drug have been reported in several U.S. cities in recent years, but few cases have been reported in Canada to date. Metro Vancouver’s local health authority sent out a public alert in January warning local users that synthetic cannabinoids had been detected in pills being sold as “down” or fentanyl.

Nick Boyce, director at the Ontario Harm Reduction Network, a non-profit that trains health-care employees working with drug users, said that cannabis is much easier to purchase in Canada so people don’t seek out synthetic forms of the drug as much. One exception he has heard of is tradespeople seeking out the drug in order to evade mandatory cannabis screening with their employers. But, he cautioned, these illicit substances are easy to procure in person or online.

Insp. Maher said parents should talk to their children about only consuming cannabis that comes from a licensed cannabis store.

“The main thing we should be concerned about is ensuring our youth do not believe that salvia or synthetic cannabinoids are safe alternatives to cannabis,” Insp. Maher said. “Synthetic cannabis is not anything close to being what cannabis is. It’s a chemical and it’s dangerous.”

Jane Buxton, harm reduction lead for the B.C. Centre for Disease Control, said if you come across someone who appears to have overdosed, administering naloxone is an appropriate first step – even if you don’t know what drug they have consumed.

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“It will take the opioid out of the picture and cause no harm if opioids are not present,” she said in an e-mailed statement.

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